A syndrome characterised by pre and postnatal muscular hypotonia, thus giving an appearance of severe brain damage; obesity, low intelligence, small hands and feet, a characteristic facies and hypogonadism, delayed attainment of developmental milestones; sometimes diabetes mellitus. In female, delayed or absent development of pubertal changes. A significant proportion of affected persons have an interstitial deletion in the long arms of chromosome 15, but most patients have a normal karotype. The affected persons often have an insatiable hunger, overeate and steal food. It is a relatively common congenital disorder with an incidence of about 1 in 10.000 live births.
First described by Prader, Labhardt and Willi in 1956 on the basis of nine children with the tetrad of small stature, mental retardation, obesity and small hands and feet. Prader and Willi reviewed the condition in 1961, expanded the phenotype and drew attention to the presence of hypotonia in infancy and the development of diabetes mellitus in later childhood.
An early account of the Prader-Labhardt-Willi syndrome can be found in a monograph, in which R. T. Brain in 1967 cites a case description made by John Langdon Down (1828-1896) in his classical text Mental Affections of Childhood and Youth. Using the term "polysarcia" Down documented details of an obese mentally retarded girl aged 14 years, who was 4 feet 4 inches in height and weighed 196 pounds. At the age of 25 years she weighed 210 pounds. Down stated "Her feet and hands remained small and contrasted remarkably with the appendages they terminated. She had no hair in the axillae and scarcely any on the pubis. She never menstruated nor did she exhibit the slightest sexual instinct.
The term Prader-Willi syndrome is now commonly used, but by historical precedence Labhart's name too belongs here.
- J. L. Down:
Mental Affections of Childhood and Youth. London, Churchill, 1887.
- A. Prader, A. Labhart, H. Willi, G. Fanconi:
Ein Syndrom von Adipositas, Kleinwuchs, Kryptorchismus und Idiotie bei Kindern und Erwachsenen, die als Neugeborene ein myotonieartiges Bild geboten haben.
VIII International Congress of Paediatrics, Copenhagen, 1956.
- A. Prader, A. Labhart, H. Willi:
Ein Syndrom von Adipositas, Kleinwuchs, Kryptorchismus und Oligophrenie nach myatonieartigem Zustand im Neugeborenenalter.
Schweizerische medizinische Wochenschrift, Basel, 1956, 86: 1260-1261.
- A. Prader, H. Willi:
Das Syndrom von Imbezilität, Adipositas, Muskelhypotonie, Hypogenitalismus, Hypogonadismus und Diabetes mellitus mit "Anamnese".
2nd Internationa Congress of Mental Retardation, Vienna. Karger, Basel & New York, 1961. Part 1: 353.
- R. T. Brain:
In: G.E.W. Wolstenholme and R. Porter, editors: Mongolism. Boston, Little, Brown and Co., Boston, 1976, pp. 1-5.
- Suzanne B. Cassidy, editor:
Prader-Willi syndrome and other chromosome 15q deletion syndromes.
NATO Advanced Study Institute Series, 1992.